Top PDF Elements of visual perception

Elements of visual perception

Elements of visual perception

and the pattern directions, predominant this and 32 difference of in origin magnitude In these two figure visual f_ circle-hexagon diffuse content difference directions, space quency by [r]

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Visual perception and processing of radial motion

Visual perception and processing of radial motion

effectively performing a proportion discrimination task. Observers could have estimated the number of coherent elements at low pedestal levels, and that of incoherent elements at high levels. It is suggested that this may be due to the probing of a mechanism sensitive to relative proportions rather than to motion energy, and this possibility is tested using orientation discrimination in Section 3.3. The results showed that the discrimination functions for orientation were unvarying across increasing pedestal values, suggesting that relative proportion judgements underlie observer performance on this task. Furthermore, a proportion discrimination account could explain how it is that adaptation affects threshold performance, but not sensitivity at higher pedestals. In order to investigate whether spatial summation of motion signals across the vertical boundary of the two stimulus alternatives may be interfering with motion processing, a temporal 2AFC experiment was performed (see Section 3.4). Neither detection nor discrimination thresholds in the t2AFC procedure were greater than in the s2AFC experiment, indicating that summation over the two stimulus alternatives did not affect this task, and adding further support for the idea that observers use relative numerosity cues. Finally, Experiment 4 (Section 3.5) shows that directing attention to one component of a radial transparent motion stimulus can result in selective adaptation to that direction of motion for some observers, but not for others, just as some, but not all, observers showed reduced sensitivity following adaptation to radial motion.
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Drawing perception : an analysis of the tectonics of drawing process and their influence on the structure of visual perception.

Drawing perception : an analysis of the tectonics of drawing process and their influence on the structure of visual perception.

through and through by the essentialist fallacy: they presume that whenever we are in a position to define a substance or activity, we must know its essence or ultimate nature” (Gallie 1954:13-35). The extreme formalist argument, that the physical content of a work of art is all that is necessary to its aesthetic appreciation, has largely been discredited by the philosophical and practical changes to those practices that are defined by the term Art. But such a hypothesis cannot be entirely replaced by the opposite assertion, that no aesthetic qualities are formal, but can be adjusted to fit a more flexible and logical assertion, an assertion that withdraws from essentialism. Indeed, just as anti-formalists argue there is context to all form; in visual arts, there is a form to all context, and I would argue that both positions are correct. This renders the debate between formalist and anti-formalist positions relatively meaningless, where it becomes an exercise in truisms or in semantic definitions of the term formal. Whilst it is undoubtedly true that history and context impact upon our perception of anything, this cannot be an objection to stating that there exist some formal properties in works of art, or that there are elements in works of art that can be considered in a formal light. If I present to you a painting with one giant blue square and one small red square, there exists a relationship between the two shapes that impacts upon us as
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Visual Perception For Robotic Spatial Understanding

Visual Perception For Robotic Spatial Understanding

What do I mean by perception? As I mentioned already, a robot capable of perception must “see and understand the environment.” This is a very compact way to express a lot of ideas, so let’s unpack it. Seeing is the ability to separate, pick out, and represent in some way or another, the important things in the environment. Understanding is harder to define, but we interpret it as the ability to transform what is seen into a meaningful and useful representation of the world. By “meaningful”, we demand that the robot does more than determine a simple 1-1 mapping between sensed data (e.g., pixels) and labels; instead, it implies the association of related information such as experiences, similarities, differences and affordances as well as a deeper recognition of structure (hierarchical, spatial, temporal) and the ability to reason about what is sensed. All of this is necessary to make inferences about the nature and purpose of the environment and the objects in it on a level similar to a human. By “useful representation” we imply that there is more to the set of pixels or points or n-dimensional vectors that are output by an algorithm. Certainly, these elements may be part of the output, or even an integral component in the representation itself, but they must be part of a larger whole that can be operated on at multiple symbolic levels. Finally, the environment is everything around the robot, including everything that can change over time and space.
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Identifying the information for the visual perception of relative phase

Identifying the information for the visual perception of relative phase

Based on these results, Bingham (2001, 2004a, b) proposed a perception-action, dynamical systems model of coordinated rhythmic movement, in which two non-linearly damped mass- spring oscillators are coordinated via a perceptual coupling function – each mass-spring is driven by the perceived phase of the other mass-spring, modified by perceived relative phase. Constrained by the empirical data described above, the model predicted that the information for perceived relative phase is the relative direction of motion of the two oscillators, the detection of which is modulated by relative speed. These are simply the two elements (direction and magnitude, respectively) of the vector quantity relative velocity, the first temporal derivative of relative position. This predicts the characteristic phenomena - 0° and 180° are distinctive because they are the mean relative phases at which the relative directions are always the same (0°) or always different (180°). 90° is the point at which the relative direction is the same half the time, and different the other half of the time, i.e. maximally variable. 0° is stable because the relative speed is zero, and the relative directions (which are consistent, and consistently the same) are therefore easily resolved; 180° is less stable because the relative speed ranges from zero to maximally different, and the relative directions (which are still consistent but now consistently different) are therefore more difficult to discriminate (because of the non-zero relative speeds). Relative direction is hardest to detect at 90° because it is maximally variable, and also because relative speed is always non-zero.
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Augmenting visual perception with gaze contingent displays

Augmenting visual perception with gaze contingent displays

GCDs can manipulate the display in a way that is noticed by the observer, by providing, for example, visual annotations on the display wherever one is looking. Alternatively, they can subtly change the content in a way that is not perceived. This thesis focuses on subtle changes on the display which lead to an overall improved impression. These have the advantage that they, from the view of the observer, do not create a specific technique they have to use or learn, but instead they end up creating a display that just has specifically improved properties, like an increased colour gamut. Since the presented techniques focus on low-level changes targeted at visual perception, their effects will be investigated using empirical methods from perceptual psychology. The investigations are designed to provide quantitative empirical evidence through psychophysical studies, that is, controlled lab experiments. The equipment used will be research equipment for the experiments, not off-the-shelf hardware, as this allows for higher precision measurements and more precise manipulations of the display content, which in turn leads to higher confidence in the experimental results.
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Subjectivity of time perception: a visual emotional orchestration

Subjectivity of time perception: a visual emotional orchestration

The aim of the present study was to examine how visual emotional content could orches- trate time perception. The experimental design allowed us to single out the share of emotion in the specific processing of content-bearing pictures, i.e., real-life scenes. Two groups of participants had to reproduce the duration (2, 4, or 6 s) of content-deprived stimuli (gray squares) or differentially valenced content-bearing stimuli, which included neu- tral, pleasant, and unpleasant pictures (International Affective Pictures Systems). Results showed that the effect of content differed according to duration: at 2 s, the reproduced duration was longer for content-bearing than content-deprived stimuli, but the difference between the two types of stimuli decreased as duration increased and was not signif- icant for the longest duration (6 s). At 4 s, emotional (pleasant and unpleasant) stimuli were judged longer than neutral pictures. Furthermore, whatever the duration, the preci- sion of the reproduction was greater for non-emotional than emotional stimuli (pleasant and unpleasant). These results suggest a dissociation within content effect on timing in the visual modality: relative overestimation of all content-bearing pictures limited to short durations (2 s), and delayed overestimation of emotional relative to neutral pictures at 4 s, as well as a lesser precision in the temporal judgment of emotional pictures whatever the duration. Our results underline the relevance for time perception models to integrate two ways of assessing timing in relationship with emotion: accuracy and precision.
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Virtual environments in visual perception : applications and challenges

Virtual environments in visual perception : applications and challenges

The use of virtual reality provides exciting opportunities for the field of visual perception. By allowing precise and indpependent manipulation of the geometric and photmetirc relationships between stimuli in the visual scene, we can examine phenomena in ways that were not previously possible and significantly enhance our understanding of perception. One potential explanation for the lack of perception studies employing virtual reality to date is the prohibitive nature of the apparatus. The virtual reality cave employed by Soranzo et al., (2013) is not only costly, it also required a large amount of space to install, totalling 3.0×3.0×2.25 metres in size. However, recent advances in virtual reality technology such as the Oculus Rift™ promise to over many of the benefits of the larger installation in a much smaller, more affordable package (Firth, 2013; Oculus, 2012). In the future therefore, we may see many more studies using virtual reality to enhance our understanding of visual perception.
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Colour and luminance interactions in the visual perception of motion

Colour and luminance interactions in the visual perception of motion

We sought to determine the extent to which red–green, colour-opponent mechanisms in the human visual system play a role in the perception of drifting luminance-modulated targets. Contrast sensitivity for the directional discrimination of drifting luminance-modulated (yellow–black) test sinusoids was measured following adaptation to isoluminant red–green sinusoids drifting in either the same or opposite direction. When the test and adapt stimuli drifted in the same direction, large sensitivity losses were evident at all test temporal frequencies employed (1–16 Hz). The magnitude of the loss was independent of temporal frequency. When adapt and test stimuli drifted in opposing directions, large sensitivity losses were evident at lower temporal frequencies (1–4 Hz) and declined with increasing temporal frequency. Control studies showed that this temporal-frequency-dependent effect could not reflect the activity of achromatic units. Our results provide evidence that chromatic mechanisms contribute to the perception of luminance-modu- lated motion targets drifting at speeds of up to at least 32 ° s ⫺ 1 . We argue that such mechanisms most
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Cerebral hemispheric studies on the visual perception of motion

Cerebral hemispheric studies on the visual perception of motion

r e c o g n i z e rooms. He f a i l e d t o c o r r e c t l y i d e n t i f y landmarks in his home c i t y and was d is o ri e n te d with regard to t h e i r geographical r e l a t i o n s h i p s . He could not draw an accurate plan of his house or c o r r e c t l y l o c a t e places on an o u t l i n e map. His drawing, copying, and c o n s tr u c t i o n a l s k i l l s were di s o rg a n i z e d . He neglected the l e f t h a l f of visual space and had dressing apraxia. He would also v a s t l y over es tim ate th e passage of time and the distance he had t r a v e l e d in his wheelchair. This l a t t e r d i s t o r t i o n of time and space is also remarked upon by Lu ria ( 197 3, Chapter 5) in cases of r i g h t hemisphere l e s i o n s .
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Pareidolia : a visual inquiry into the perception of ambiguous images

Pareidolia : a visual inquiry into the perception of ambiguous images

After some early exploratory works on wood slabs I returned to painting on canvas, again using the splatter technique to simulate natural textures such as rocks. At times, very diverse content appeared which I pursued although the paintings seemed not to be cohesive or appealing to me. Some works were realistic in parts and others were highly decorative and pattern-like (Figures 57 and 58). The five people in Queue were perceived as outlines of figures and then ‘dressed’ according to my perception of their character. A sixth individual was left untouched as an example of how some figures can appear without embellishment.
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Effect of Non-Visual Stimulus on Color Perception

Effect of Non-Visual Stimulus on Color Perception

The experiment conducted above was repeated except that observers were required to visually compare each treated sample with a control (no finish applied) while touching the samples for the entire duration of the assessment. Color differences between control and test samples were at suprathreshold level since samples were assessed within a given wash set (either 1, 5 and 10 washes). For example a sample washed 5 times and treated with 2% softener was compared to a control that was washed 5 times but no softness applied. The observers were not told how to touch the samples, except to handle the samples well as shown in Figure 15. The observers were also asked to rate the hand of the fabric prior to providing a visual assessment, in order to force the processing of tactile responses. Hence, the color difference perception, if any, between visual alone and both visual and touch could be determined. Consequently, the effect of fabric hand on color difference perception could be assessed. Figure 22 shows a comparison of visual color- difference data (without tactile response) to visual color-difference data with tactile response. In general, the perceived color difference between samples was lower when a tactile response was included than when no touching of samples was allowed. Figure 23 shows a graph of the difference (DV visual alone - DV visual + hand )
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Threat modulates perception of looming visual stimuli

Threat modulates perception of looming visual stimuli

2 Among the most critical of visual functions is the detection of potentially hazardous or threatening aspects of the environment. For example, objects on a collision course with an observer must be quickly identified to allow sufficient time to prepare appropriate defensive or avoidant responses. Directly approaching objects produce a specific accelerating pattern of optical expansion, which in theory exactly specifies time-to-collision independent of object size or distance [1], and which triggers stereotyped defensive responses in both monkeys [1] and human infants [2]. Psychophysical results have similarly suggested sensitivity to looming at early stages of visual processing [3]. Such findings indicate specialization of the visual system to detect and react to such ‘looming' stimuli, and have contributed to the traditional view of
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Some Questions of Actualization of Visual Perception in The Language

Some Questions of Actualization of Visual Perception in The Language

Abstract: the work considers the language actualization of the visual, the perception is the process of a sequential transition of the results of reflection, awareness, construction (simulation) and is proved that, denoting denotative situations from the level of the conceptual structure to the level of the semantic structure of linguistic signs: the subject (denotative) situation concept of the situation cognitive scene the lexical (grammatical) meaning of a simple linguistic sign or the proposition of a composite sign of a language (a derivative word- composite, as a semantic form of the actualization of meaning.
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Drawing perception : an analysis of the tectonics of drawing process and their influence on the structure of visual perception.

Drawing perception : an analysis of the tectonics of drawing process and their influence on the structure of visual perception.

KOZBELT, A. 2001 Artists as Experts in Visual Cognition. Visual Cognition Vol. 8, pp. 705-723. LOCHER, P. J., KRUPINSKI, E. A., MELLO-THOMS, C., & NODINE, C. F. 2008 ‘Visual interest in pictorial art during an aesthetic experience’, in SAGI, D. & REEVES, A. Spatial Vision, 21, pp. 55-77.

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Medical Diagnosis and Visual Perception - An Evaluation of Usability

Medical Diagnosis and Visual Perception - An Evaluation of Usability

In the Panel “From Data to Diagnosis” [SG10] at SIGGRAPH 2010, panellist Cindy Grimm challenged participants and co-speakers by asking to prove the usefulness of their graphics products for medical diagnosis. She is right in her claim that usefulness of graphics algorithms for a specific diagnosis is hardly ever seriously challenged. For medical and other applications, there is a lack of evaluation of usefulness of processes and tools beyond efficiency and usability. Often the reason for using 3d algorithms over a 2d presentation or vice versa seems to stem from the appropriateness as individually seen by doctors and medical staff in charge. But because the visual interpretation of medical images is often crucial to a patient’s life, moving from 2d images as a basis for making decisions on a patient’s life to 3d images (where rendering algorithms manipulate data in several ways) has to be well controlled and understood.
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Mental Space Elements of Vietnamese and English Perception Verbs

Mental Space Elements of Vietnamese and English Perception Verbs

Abstract: Perception is the procedure by which we interpret information about the environment that surrounds us. We can also say that perception is the gate to cognition. The perception process gives feedback about others and us. It is not always based on true picture of reality and we behave as though our perceptions are real. There are three key attributes to perception. The first is raw data. That is the information we experience. The second is the mental process, which is unseen but affected by things. The third is the product or that is our perception, sensing, or interpretation of our experience. In this article, we examine part of the second, the mental space elements of the perception verbs, Vietnamese and English in contrast. We inspected and collected 3,946 sentences with perception verbs as research data from two sets of English-Vietnamese, Vietnamese-English bilingual novels: The adventures of Sherlock Holmes and Love after war. We then used classify, statistic, descriptive, analysis, and contrastive methods to examine the research data. The results we have achieved for this research question are as followed. Basic mental space elements of the perception verbs include tangible and intangible factors. Tangible factors are preceptor/perceiver/experience/agent, perceived/stimulus, and perception organs. Intangible factors include spatial elements, ontological elements and information elements. Spatial elements are location, distance, path, direction, definition, layer, planning. Ontological elements are volition (volitional and non-volitional), way of cognition, sentient ability, culture, knowledge, ethnicity, geographic location, and way of thinking. Information elements are viewpoint and target.
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The effect of indentation force and displacement on visual perception of compliance

The effect of indentation force and displacement on visual perception of compliance

Visual information has been shown to greatly affect our ability to perceive the compliance of objects [12]. Kuschel et al focused on the integration and separation of vision and touch during haptic perception. Their results suggested that contribution of a sense cue depends upon its level of reliability at any given time [17]. Johnson, Burton & Ro (2006) investigated visually induced feelings of touch. Their results indicate that when haptic feedback is distorted, participants relied more on visual feedback. This further emphasizes the importance of visual information in LS. Using a pseudo-haptic feedback system, Li et al showed that visual information can be used to correctly identify virtual tumors [18]. By manipulating the speed and size of an on- screen cursor, they were able to simulate varying stiffness levels. Hachisu et al augmented vision and tactile vibration cues in a pseudo-haptic feedback system in an attempt to improve the vibrational sensory experience while exploring the material stiffness of fabrics and virtual objects [19]. Our previous work has investigated the effects of the varying types of visual sources on compliance discrimination [11]. Using four ‘two alternative forced choice’ (2AFC) indention tasks in which either direct visual cues, 2D indirect visual cues or no visual cues were present. Results showed that visual information influences compliance perception.
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What is a State of Visual Perception?   Robert Hudson

What is a State of Visual Perception? Robert Hudson

As I suggested in the Introduction, there is a strong temptation with the visual masking experiments we are considering to identify the states of neural activity indicated by the fMRI images of BOLD responses with their correlative states of visual awareness. To make the point more graphic, imagine (hypothetically) a case where a subject in the SWI masking experiment can turn a knob moving the masks closer and closer to the target bar, and in turn can watch the target bar fade in and out of awareness, while contemporaneously looking at an fMRI monitor to see how his neuronal firing increases or decreases with the level of awareness. We can easily imagine the subject exclaiming, upon watching the correlation, “Wow! There‟s my awareness of the target bar fading in and out!” The legitimacy of the subject‟s pronouncement here can be attributed in part to the highly circumscribed nature of her experience: there is nothing else going on but the movement of the masks which leads to the changing appearance of the target bar. But could the vacillating BOLD response be due solely to the movements of the masks? Tse et al. conduct experiments which involve subjects observing only the moving masks, without the presence of the target bar, and the BOLD responses found in this case occurred only in non- occipital areas, as did BOLD signals responding only to the flashing of the target bar (see Tse et al. 2005, p. 17180 and Macknik 2006, p. 203). Thus, there seems to be, at the very least, a strong correlation between the fading in and out of the target bar and the BOLD responses Tse et al. have identified.
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Identifying the information for the visual perception of relative phase

Identifying the information for the visual perception of relative phase

(Wilson, Bingham & Craig, 2003). The judgment data mirrored the movement pattern – judgments of 90° are highly variable, 180° less so and 0° hardly at all. This suggested that the pattern emerges in movement as a result of how well information about the conditions is detected. The second stream tested this by manipulating the perceptual feedback used to control a coordinated movement and measuring how movement stability changes in response (Bogaerts, Buekers, Zaal, & Swinnen (2003); Mechsner, Kerzel, Knoblich & Prinz, 2001; Wilson, Collins & Bingham, 2005a). Movement stability varied as a function of the relative phase of the feedback, rather than the relative phase of the movement. Non-0° movements are therefore not intrinsically unstable - if the participant can readily discriminate the information used to perform the task, then this stable perception allows for stable movement. These experimental manipulations suggest that movement stability is largely a function of perceptual stability 1 . The question remains - what is the identity of the perceptual information being used?
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